CVE-2021-33500
mediumpriority · track · 31EPSS 0.019 · 80 %ileEURUUSEPSS · scored 2026-10-27
PuTTY before 0.75 on Windows allows remote servers to cause a denial of service (Windows GUI hang) by telling the PuTTY window to change its title repeatedly at high speed, which results in many SetWindowTextA or SetWindowTextW calls. NOTE: the same attack methodology may affect some OS-level GUIs on Linux or other platforms for similar reasons.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (6)
Products and version ranges known to be affected.
also known as (4)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (9)
External citations — patches, advisories, analysis.
- https://docs.ssh-mitm.at/puttydos.htmlcnnvd
- https://github.com/ssh-mitm/ssh-mitm-plugins/blob/main/ssh_mitm_plugins/ssh/putty_dos.pycnnvd
- https://www.chiark.greenend.org.uk/~sgtatham/putty/changes.htmlcnnvd
- https://docs.ssh-mitm.at/puttydos.htmlenisa_euvd
- https://github.com/ssh-mitm/ssh-mitm-plugins/blob/main/ssh_mitm_plugins/ssh/putty_dos.pyenisa_euvd
- https://www.chiark.greenend.org.uk/~sgtatham/putty/changes.htmlenisa_euvd
- https://docs.ssh-mitm.at/puttydos.htmlExploitThird Party Advisorynvd
- https://github.com/ssh-mitm/ssh-mitm-plugins/blob/main/ssh_mitm_plugins/ssh/putty_dos.pyExploitThird Party Advisorynvd
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